{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-63576",
        "assignerOrgId": "91579145-5d7b-4cc5-b925-a0262ff19630",
        "state": "PUBLISHED",
        "assignerShortName": "bcorg",
        "dateReserved": "2026-07-16T23:51:51.306Z",
        "datePublished": "2026-10-02T07:07:02.513Z",
        "dateUpdated": "2026-10-06T19:31:40.267Z"
    },
    "containers": {
        "cna": {
            "providerMetadata": {
                "orgId": "91579145-5d7b-4cc5-b925-a0262ff19630",
                "shortName": "bcorg",
                "dateUpdated": "2026-10-02T07:07:02.513Z"
            },
            "title": "URI name constraints checked against a mis-parsed host",
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "lang": "en",
                            "cweId": "CWE-295",
                            "description": "CWE-295 Improper Certificate Validation",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "impacts": [
                {
                    "descriptions": [
                        {
                            "lang": "en",
                            "value": "Integrity (bypass of permitted/excluded URI name constraints in certification path validation)"
                        }
                    ]
                }
            ],
            "affected": [
                {
                    "vendor": "Legion of the Bouncy Castle Inc.",
                    "product": "bc-csharp",
                    "collectionURL": "https://www.nuget.org/packages/BouncyCastle.Cryptography",
                    "packageName": "BouncyCastle.Cryptography",
                    "repo": "https://github.com/bcgit/bc-csharp",
                    "programFiles": [
                        "crypto/src/pkix/PkixNameConstraintValidator.cs",
                        "crypto/src/pkix/NameConstraintUtilities.cs",
                        "crypto/src/pkix/NameConstraintUri.cs"
                    ],
                    "versions": [
                        {
                            "status": "affected",
                            "version": "0",
                            "lessThan": "2.7.0",
                            "versionType": "semver"
                        }
                    ],
                    "defaultStatus": "unaffected"
                }
            ],
            "descriptions": [
                {
                    "lang": "en",
                    "value": "Improper certificate validation in PkixNameConstraintValidator (ExtractHostFromURL) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a name-constrained subordinate CA, or anyone able to obtain certificates with chosen subjectAltName URIs from such a CA, to bypass permitted or excluded uniformResourceIdentifier name constraints during certification path validation via a URI whose path, query, fragment or userinfo contains characters such as '@' or ':', because the host was extracted by string slicing without first isolating the RFC 3986 authority component, so the host compared against the constraints could differ from the URI's actual host.",
                    "supportingMedia": [
                        {
                            "type": "text/html",
                            "base64": false,
                            "value": "Improper certificate validation in PkixNameConstraintValidator (ExtractHostFromURL) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a name-constrained subordinate CA, or anyone able to obtain certificates with chosen subjectAltName URIs from such a CA, to bypass permitted or excluded uniformResourceIdentifier name constraints during certification path validation via a URI whose path, query, fragment or userinfo contains characters such as '@' or ':', because the host was extracted by string slicing without first isolating the RFC 3986 authority component, so the host compared against the constraints could differ from the URI's actual host."
                        }
                    ]
                }
            ],
            "references": [
                {
                    "url": "https://github.com/bcgit/bc-csharp/wiki/CVE-2026-63576",
                    "tags": [
                        "vendor-advisory"
                    ]
                },
                {
                    "url": "https://github.com/bcgit/bc-csharp/commit/f196a22bbf7765cc19b0c4f4645c74ea7ad35e09",
                    "tags": [
                        "patch"
                    ]
                }
            ],
            "metrics": [
                {
                    "format": "CVSS",
                    "scenarios": [
                        {
                            "lang": "en",
                            "value": "GENERAL"
                        }
                    ],
                    "cvssV4_0": {
                        "attackVector": "NETWORK",
                        "attackComplexity": "LOW",
                        "attackRequirements": "PRESENT",
                        "privilegesRequired": "NONE",
                        "userInteraction": "NONE",
                        "vulnConfidentialityImpact": "NONE",
                        "subConfidentialityImpact": "NONE",
                        "vulnIntegrityImpact": "HIGH",
                        "subIntegrityImpact": "NONE",
                        "vulnAvailabilityImpact": "NONE",
                        "subAvailabilityImpact": "NONE",
                        "exploitMaturity": "NOT_DEFINED",
                        "Safety": "NOT_DEFINED",
                        "Automatable": "NOT_DEFINED",
                        "Recovery": "NOT_DEFINED",
                        "valueDensity": "NOT_DEFINED",
                        "vulnerabilityResponseEffort": "NOT_DEFINED",
                        "providerUrgency": "NOT_DEFINED",
                        "version": "4.0",
                        "baseSeverity": "HIGH",
                        "baseScore": 8.2,
                        "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N"
                    }
                }
            ],
            "credits": [
                {
                    "lang": "en",
                    "value": "Discovered by Claude, Anthropic's AI assistant, and triaged by the Anthropic security team in collaboration with Anthropic Research.",
                    "type": "finder"
                }
            ],
            "source": {
                "discovery": "EXTERNAL"
            },
            "x_generator": {
                "engine": "Claude Opus 5.5"
            },
            "x_antReportIds": [
                "ANT-2026-R05HVR25"
            ]
        },
        "adp": [
            {
                "metrics": [
                    {
                        "other": {
                            "type": "ssvc",
                            "content": {
                                "timestamp": "2026-10-06T19:21:06.114263Z",
                                "id": "CVE-2026-63576",
                                "options": [
                                    {
                                        "Exploitation": "none"
                                    },
                                    {
                                        "Automatable": "no"
                                    },
                                    {
                                        "Technical Impact": "partial"
                                    }
                                ],
                                "role": "CISA Coordinator",
                                "version": "2.0.3"
                            }
                        }
                    }
                ],
                "title": "CISA ADP Vulnrichment",
                "providerMetadata": {
                    "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
                    "shortName": "CISA-ADP",
                    "dateUpdated": "2026-10-06T19:31:40.267Z"
                }
            }
        ]
    }
}